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Hairy croton (Croton hirtus)

In Australia, hairy croton is currently recorded at one site near Weipa, Queensland, and appears to have potential to become an environmental weed. It is also recorded as a weed of agricultural and disturbed habitats.

Key facts

Type: Weed, herb.

Native to: Tropical areas of North and South America.

Established in: QLD.

Other names: Croton glandulosus subsp. hirtus, Croton glandulosus var. hirtus, Brachystachys hirta.

Identification

  • This upright annual herb grows up to 1 m high and has an offensive odour when crushed.
  • The whole plant is covered with stiff, star-shaped hairs that may irritate skin.
  • Its roughly egg-shaped leaves are 2.5–7.5 cm long and 1–5 cm wide, with finely toothed edges.
  • Separate male and female flowers grow on the same plant in spike-like clusters up to 4 cm long; female flowers are green and male flowers are white.
  • The green, three-lobed capsules are about 4 mm across and release usually three grey-brown, finely ribbed seeds about 3 mm long.

Where it grows

In Australia it has been recorded at one site near Weipa, Queensland, and grows in disturbed places such as roadsides, gardens, pastures and cultivated areas.

Why it matters

  • It is recorded as a weed of agricultural and disturbed habitats.
  • In south-east Asia it invades orchards, tea plantations, upland rice, tobacco, peanut and vegetable crops.
  • It appears to have potential to become an environmental weed.

How it spreads

  • Hairy croton spreads primarily by seed, with ants reported as the main animal dispersal vector.
  • There is also evidence that machinery spreads it.
  • Water movement can spread it along watercourses.

Control options

  • The Australian population has been controlled with registered herbicides and/or fire.
  • Follow-up treatments are required because numerous seedlings emerge from beneath poisoned plants.
  • Consult the Australian Pesticides and Veterinary Medicines Authority for chemical information.

Hygiene and washdown

  • Machinery is a reported spread pathway, so check and clean machinery before moving it between sites.
  • Water movement can spread seeds along watercourses.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Declared pest (C1), prohibited. C1 Exclusion: to be kept out of WA, or out of the parts of WA where it is not established. Report any sighting to DPIRD. It must not be brought into WA (prohibited organism).
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Declared weed. Weeds Australia lists it as a declared weed in the NT under the Weeds Management Act 2001. Check the NT declared weeds list for its class and what it requires.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)

Sources